'use strict';
//const collection = [1, [2], [3, 4]];
function double_to_one(collection) {
     let a=(collection+'');
     console.log( a);
      let arr=a.split(',');
     console.log( arr);
     let s1=arr.map(function(x){
              return Number(x);
     });
     console.log( s1);
     return s1;
    
  //在这里写入代码
}

module.exports = double_to_one;
